WELDING OF GROOVE RAILS BY INNERSHIELD WELDING PROCEDURE

摘要

In the past, tram tracks, as a special group of track construction, have received less attention in comparison to standard railway tracks. During supervision of the reconstruction of various types of tram tracks in Zagreb (about 85 km of tram tracks reconstructed in the period 1994-2006), it was established that the major percentage of local damage occurred at the welded rail joints. Repair of faulty rail welds is always expensive and requires stopping both tram and road traffic, especially in those sections where they share the same traffic surface. Aluminothermic and manual metal arc welding are standard procedures used on tram tracks in both Zagreb and Osijek. This paper describes the Innershield welding procedure, which has not yet been used for grooved rail welding in Croatia. The fatigue strength of this weld type was tested in order to determine its applicability for welding tram rails. To ensure comprehensiveness, fatigue strength was also tested for the aluminothermic and manual metal arc welded rail joints. Testing of grooved rail welds was performed on a Zwick Z600 low frequency pulse generator with the frequency of 6.0 Hz and up to a total of 2 million cycles. Ri-60 700 grade rail types (minimum tensile strength 680 N/mm{sup}2) were used in making the specimen welds needed for testing. From our point of view, and based on the favorable testing results, the Innershield welding procedure is more suitable for the welding of standard grooved tram rails. The favorable results of this welding method have encouraged the Zagreb Electric Tramway Company to consider adopting Innershield welding as a standard welding procedure for city tram tracks.